Related links:

Rotation of the Sun

The Sun, like most other astronomical objects
(planets, asteroids, galaxies, etc.), rotates on
its axis. Unlike Earth and other solid objects, the entire Sun doesn't rotate
at the same rate. Because the Sun is not solid, but is instead a giant ball
of gas and plasma,
different parts of the Sun spin at different rates.

We can tell how quickly the surface of
the Sun is rotating by observing the motion of structures, such as sunspots,
on the Sun's visible surface. The regions of the Sun near its equator rotate
once every 25 days. The Sun's rotation rate decreases with increasing latitude,
so that its rotation rate is slowest near its poles. At its poles the Sun rotates
once every 36 days!

The interior of the Sun does not
spin the same way as does its surface. Scientists believe that the inner regions
of the Sun, including the Sun's core and
radiative zone, do rotate more like a solid body. The outer parts of the Sun,
from the convective
zone outward, rotate at different rates that vary with latitude. The boundary
between the inner parts of the Sun that spin together as a whole and the outer
parts that spin at different rates is called the "tachocline".

The behavior of the Sun's magnetic
field is strongly influenced by the combination of convective currents,
which bring the charged plasma from deep within the Sun to the Sun's surface,
and the differential rotation of the outer layers of the Sun. The complex,
swirling motions that result make
a tangled mess of magnetic field lines at the Sun's surface. Differential
rotation is apparently the main driver of the 11-year sunspot
cycle and the associated 22-year solar
cycle. The notion that differential rotation and convective motion drive
these cycles was first put forth in 1961 by the American astronomer Horace
Babcock, and is now known as the Babcock Model.

(Note: If you cannot see the movie of the rotating Sun on this page
you may need to download the latest QuickTime player.)

Shop Windows to the Universe Science Store!

Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store.

You might also be interested in:

Plasma is known as the fourth state of matter. The other three states are solid, liquid and gas.In most cases, matter on Earth has electrons that orbit around the atom's nucleus. The negatively charged...more

Most of the energy we receive from the Sun is the visible (white) light emitted from the photosphere. The photosphere is one of the coolest regions of the Sun (6000 K), so only a small fraction (0.1%)...more

Sunspots are dark, planet-sized regions that appear on the "surface" of the Sun. Sunspots are "dark" because they are colder than the areas around them. A large sunspot might have a temperature of about...more

The solar core is made up of a really hot and dense gas (in the plasma state). The temperature of 15 million kelvins (27 million degrees Faranheit) keeps the core at a gaseous state. The core is where...more

The Sun has a very large and very complex magnetic field. The magnetic field at an average place on the Sun is around 1 Gauss, about twice as strong as the average field on the surface of Earth (around...more

You may have heard of sunspots that sometimes dot the "surface" of the nearest star, our Sun. Well, other stars have spots too. They are called starspots and are relatively cool, dark regions on the visible...more

Sunspots are caused by very strong magnetic fields on the Sun. The best way to think about the very complicated process of sunspot formation is to think of magnetic "ropes" breaking through the visible...more